Data storage and retrieval systems are used to store information provided by one or more host computer systems. Such data storage and retrieval systems receive requests to write information to one or more secondary storage devices, and requests to retrieve information from those one or more secondary storage devices. Upon receipt of a write request, the system stores information received from a host computer in a data cache. In certain implementations, a copy of that information is also stored in a nonvolatile storage device. Upon receipt of a read request, the system recalls information from the one or more secondary storage devices and moves that information to the data cache. Thus, the system is continuously moving information to and from storage devices, and to and from the data cache.
One or more controllers coordinate receipt of information from one or more host computers, and the movement of information to and from the data cache and storage devices. Those one or more controllers are powered by one or more internal power buses. In addition, those one or more controllers are each interconnected with a battery-backup assembly. What is needed is an apparatus and method to selectively provide power to a plurality of battery-backup assemblies.